It seems the gallery has a limit of 100 images at a time to be uploaded.
This is fine if it would stop you at that limit, opposed to uploading over 200+ images, pressing continue and THEN it telling you in small print about the limit...  you've just wasted all that time uploading the additional images for nothing.

besides that (annoying behaviour - just wasted a lot of time) - is there a way to increase this 100 picture upload limit in the gallery?

I couldn't find the limit in the gallery settings, nor the group-permissions?

thanks in advance

There's no IPS setting to change this 100 image limit.  

IPS is doing a sweep of IP.Gallery "soon" so we might see some improvements in this area.

As Joel has mentioned, we're doing a Gallery update soon and I'll ensure this is looked at.